Please don't leave them if you haven't seen the mama cat. Find some help nearby, like everyone else has said. Our little Cleo was all alone when she was found -- she was estimated to be about 5 days old and yowling her head off. Mama cat was nowhere to be seen and hadn't been, so something probably happened to her. And all Cleo's littermates were found dead so Cleo was probably not far off if she hadn't been found when she was. Now we are the lucky ones to have her. Good luck and keep us posted!